Apremilast, chemically known as N-(2-((1S)-1-(3-ethoxy-4-methoxyphenyl)-2-(methylsulfonyl) ethyl)-2,3-dihydro-1,3-dioxo-1H-isoindol-4-yl)-acetamide, is represented by formula (I).

It is an anti-inflammatory drug, specifically inhibits PDE4 and also inhibits spontaneous production of TNF-alpha from human rheumatoid synovial cells.
Apremilast is first disclosed in U.S. Pat. No. 6,020,358. It also describes process for the preparation of Apremilast, which involves coupling of 3-acetamido phthalic anhydride and 1-(3-alkoxy-4-alkoxyphenyl)-2-(methylsulfonyl) ethanamine in the presence of acetic acid, followed by resolution using chromatography.
The process for preparation of Apremilast of formula (I) is also disclosed in WO2012083153A1, WO2013126360, WO2013126495, U.S. Pat. Nos. 7,427,638, 8,242,310, CN 104761474, CN 104803897 and CN 103864670.
The process disclosed in the above mentioned patents/patent applications is having following disadvantages:
a) Use of Lithium hexamethyl disilazide is hazardous and reports lower yield (Yield=39%).
b) Use of very expensive reagents like (R, S)-t-Bu-Josiphos or Rh (cod)2 OTf.
c) Purification by using column chromatography techniques, which is very difficult in commercial scale.
d) Low yield & Low purity.
In view of the preparation methods available for Apremilast, there is a need for simple and cost effective process for the preparation of Apremilast with high optical purity by avoiding the use of expensive starting raw materials.